Last Friday, a group of young soccer players -- all 13- and 14-year-old girls -- and their chaperones traveled from Oregon to Washington state for a weekend tournament. Less than two days later, nine people became severely ill with vomiting and diarrhea.

According to public health officials, most of those who got sick ate from the same packaged cookies, which, it seems, were stored in a reusable grocery bag left in the hotel room of the first player to take ill.

When scientists tested the bag, it showed positive results for the norovirus and proved that the majority of people became sick even without person-to-person contact.

Noroviruses cause an estimated 21 million cases of gastroenteritis a year, resulting in approximately 70,000 hospitalizations and 800 deaths. And they're notoriously resilient, capable of living for prolonged periods on surfaces.